This is the reason your seasonal allergies seem to never end

Climate change is making life worse for allergy sufferers.

As temperatures have warmed over the past few decades, the change in the seasons has brought a different pattern to how we normally perceive our calendar year. As a result, the growing seasons which is the time between the last winter freeze and the first fall freeze is getting longer.

That means the plant’s flower and pollen produced is being prolonged, causing those with allergies to suffer from symptoms longer, according to a recent Climate Central study.

Climate Central said it’s been tracking the period when plants grow, flower, and send out pollen. They found that over the last half-century, the growing season has got longer in 83% of the 201 cities analyzed in its study. The season has been extended by two weeks on average across the US, according to the study, with 34 cities suffering at least four weeks of extended allergies.

Cities in Oregon and New Mexico had the largest increases, according to the study, with some places experiencing an increase of two months or more.

Per the report, CO2 emissions are the culprit:

According to laboratory studies, CO2 emissions can also spur pollen production directly. At atmospheric CO2 concentrations of 600 parts per million — which we could hit around 2060 on our current trajectory — ragweed pollen production could double relative to 2000 CO2 levels. In those conditions, each grain of ragweed pollen could also get 1.7 times more allergically potent. The story is similar for the production of Timothy Grass pollen, a major allergen in the early summer. Our CO2 emissions may be invisible, but the resulting pollen levels will clearly be felt.